Transgenic Plants / Genetically Modified Crops
(Gm Crops)
Weeds are a constant problem in crop fields. Weeds not only
compete with crops for sunlight, water, nutrients and space but also a carrier
for insects and diseases. If left uncontrolled, weeds can reduce crop yields
significantly.
Transgenic plants contain a novel DNA introduced into its
genome.
Glyphosate herbicide produced by Monsanto, USA company under
the trade name ‘Round up’ kills plants by blocking the 5-enopyruvate shikimate-3
phosphate synthase (EPSPS) enzyme, an enzyme involved in the biosynthesis of
aromatic amino acids, vitamins and many secondary plant metabolites. There are
several ways by which crops can be modified to be glyphosate-tolerant.
One strategy is to incorporate a soil bacterium gene that produces
a glyphosate tolerant form of EPSPS. Another way is to incorporate a different
soil bacterium gene that produces a glyphosate degrading enzyme.
·
Weed control improves higher crop yields;
·
Reduces spray of herbicide;
·
Reduces competition between crop plant and weed;
·
Use of low toxicity compounds which do not remain active in the
soil; and
·
The ability to conserve soil structure and microbes.
Trade name ‘Basta’ refers to a non-selective herbicide containing
the chemical compound phosphinothricin. Basta herbicide tolerant gene PPT (L-phosphinothricin)
was isolated from Medicago sativa plant. It inhibits the enzyme
glutamine synthase which is involved in ammonia assimilation. The PPT gene was
introduced into tobacco and transgenic tobacco produced was resistant to PPT.
Similar enzyme was also isolated from Streptomyces hygroscopicus with
bar gene encodes for PAT (Phosphinothricin acetyl transferase) and was
introduced into crop plants like potato and sugar-beet and transgenic crops
have been developed.
i. Bt Cotton
Bt cotton is a genetically modified organism (GMO) or genetically
modified pest resistant plant cotton variety, which produces an insecticide
activity to bollworm.
Strains of the bacterium Bacillus thuringiensis produce
over 200 different Bt toxins, each harmful to different insects. Most Bt toxins
are insecticidal to the larvae of moths and butterflies, beetles, cotton
bollworms and gatflies but are harmless to other forms of life.
The genes are encoded for toxic crystals in the Cry group of
endotoxin. When insects attack and eat the cotton plant the Cry toxins are
dissolved in the insect’s stomach.
The epithelial membranes of the gut block certain vital nutrients
thereby sufficient regulation of potassium ions are lost in the insects and
results in the death of epithelial
cells in the intestine membrane which leads to the death of the larvae.
Advantages
The advantages of Bt cotton are:
·
Yield of cotton is increased due to effective control of
bollworms.
·
Reduction in insecticide use in the cultivation of Bt cotton
·
Potential reduction in the cost of cultivation.
Disadvantages
Bt cotton has some limitations:
·
Cost of Bt cotton seed is high.
·
Effectiveness up to 120 days after that efficiency is reduced
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Ineffective against sucking pests like jassids, aphids and
whitefly.
·
Affects pollinating insects and thus yield.
ii. Bt Brinjal
The Bt brinjal is another transgenic brinjal created by inserting
a crystal protein gene (Cry1Ac) from the soil bacterium Bacillus thuringiensis
into the genome of various brinjal cultivars. The insertion of the
gene, along with other genetic elements such as promoters, terminators and an
antibiotic resistance marker gene into the brinjal plant is accomplished using
Agrobacteriummediated genetic transformation. The Bt brinjal has been
developed to give resistance against
Lepidopteron insects, in particular the Brinjal Fruit and Shoot Borer (Leucinodes
orbonalis).
iii. Dhara Mustard Hybrid (DMH)
DMH -11 is transgenic mustard developed by a team of scientists Centre for Genetic Manipulation of Crop Plants at Delhi University under Government sponsored project. It is geneticallymodifiedvarietyofHerbicideTolerant (HT) mustard. It was created by using “barnase/ barstar” technology for genetic modification by adding genes from soil bacterium that makes mustard, a self-pollinating plant. DMH -11 contains three genes viz. Bar gene, Barnase and Barstar sourced from soil bacterium. The bar gene had made plant resistant to herbicide named Basta.
Many plants are affected by virus attack resulting in series loss
in yield and even death. Biotechnological intervention is used to introduce
viral resistant genes into the host plant so that they can resist the attack by
virus. This is by introducing genes that produce resistant enzymes which can
deactivate viral DNA.
Agrobacterium mediated genetic engineering technique was followed to
produce Flavr-Savr tomato, i.e., retaining the natural colour and flavor of
tomato.
Through genetic engineering, the ripening process of the tomato is
slowed down and thus prevent it from softening and to increase the shelf life.
The tomato was made more resistant to rotting by Agrobacterium mediated
gene transfer mechanism of introducing an antisense gene which interferes with
the production of
Golden rice is a variety of Oryza sativa (rice) produced
through genetic engineering of biosynthesized beta-carotene, a precursor of
Vitamin-A in the edible parts of rice developed by Ingo Potrykus and his group.
The aim is to produce a fortified food to be grown and consumed in areas with a
shortage of dietary Vitamin-A, which kills so many children under five year
age. Golden rice differs from its parental strain by the addition of three
beta-carotene biosynthesis genes namely ‘psy’ (phytoene synthase) from daffodil
plant Narcissus pseudonarcissus and ‘crt-1’ gene from the soil
bacterium Erwinia auredorora and ‘lyc’ (lycopene cyclase) gene from
wild-type rice endosperm.
The endosperm of normal rice, does not contain beta-carotene.
Golden-rice has been genetically altered so that the endosperm now accumulates
Beta-carotene. This has been done using Recombinant DNA technology. Golden rice
can control childhood blindness - Xerophthalmia.
GM Food - Benefits
·
High yield without pest
·
70% reduction of pesticide usage
·
Reduce soil pollution problem
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Conserve microbial population in soil
Risks - believed to
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Affect liver, kidney function and cancer
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Hormonal imbalance and physical disorder
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Anaphylactic shock (sudden hypersensitive reaction) and allergies.
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Adverse effect in immune system because of bacterial protein.
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Loss of viability of seeds show in terminator seed technology of
GM crops.
Synthetic polymers are non-degradable and pollute the soil and
when burnt add dioxin in the environment which cause cancer. So, efforts were
taken to provide an alternative eco-friendly biopolymers. Polyhydroxyalkanoates
(PHAs) and polyhydroxybutyrate (PHB) are group of degradable biopolymers which
have several medical applications such as drug delivery, scaffold and heart
valves. PHAs are biological macromolecules and thermoplastics which are
biodegradable and biocompatible.
Several microorganisms have been utilized to produce different
types of PHAs including Gram-positive like Bacillus megaterium, Bacillussubtilis
and Corynebacterium glutamicum,
Gram-negative bacteria like group of Pseudomonas sp. and Alcaligenes
eutrophus.
Polylactic acid or polylactide (PLA) is a biodegradable and
bioactive thermoplastic. It is an aliphatic polyester derived from renewable
resources, such as corn starch, cassava root, chips or starch or sugarcane. For
the production of PLA, two main monomers are used: lactic acid, and the cyclic
diester, lactide. The most common route is the ring-opening polymerization of lactide with
metal catalysts like tin octoate in solution.The metal-catalyzed reaction
results in equal amount of d and polylactic acid.
The green fluorescent protein (GFP) is a protein containing 238
amino acid residues of 26.9 kDa that exhibits bright green fluorescence when
exposed to blue to ultraviolet range (395 nm). GFP refers to the protein first
isolated from the jellyfish Aequorea victoria. GFP is an excellent tool
in biology due to its ability to form internal chromophore without requiring
any accessory cofactors, gene products, enzymes or substrates other than
molecular oxygen. In cell and molecular biology, the GFP gene is frequently
used as a reporter of expression. It has been used in modified forms to make
biosensors.
Biopharming also known as molecular pharming is the production and
use of transgenic plants genetically engineered to produce pharmaceutical
substances for use of human beings. This is also called “molecular farming
or pharming”. These plants are different from medicinal plants which
are naturally available. The use of plant systems as bioreactors is gaining
more significance in modern biotechnology. Many pharmaceutical substances can
be produced using transgenic plants. Example: Golden rice
It is defined as the use of microorganisms or plants to clean up
environmental pollution. It is an approach used to treat wastes including
wastewater, industrial waste and solid waste. Bioremediation process is applied
to the removal of oil, petrochemical residues, pesticides or heavy metals from
soil or ground water. In many cases, bioremediation is less expensive and more
sustainable than other physical and chemical methods of
remediation.Bioremediation process is a cheaper and eco-friendly approach and
can deal with lower concentrations of contaminants more effectively. The
strategies for bioremediation in soil and water can be as follows:
·
Use of indigenous microbial population as indicator species for
bioremediation process.
·
Bioremediation with the addition of adapted or designed microbial
inoculants.
·
Use of plants for bioremediation - green technology.
Some examples of bioremediation technologies are:
·
Phytoremediation - use of plants to bring about
remediation of environmental pollutants.
·
Mycoremediation - use of fungi to bring about remediation
of environmental pollutants.
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Bioventing is the process that increases the oxygen or air flow to
accelerate the degradation of environmental pollutants.
·
Bioleaching is the use of microorganisms in solution to recover metal
pollutants from contaminated sites.
·
Bioaugmentation is the addition of selected microbes to
speed up degradation process.
·
Composting is the process by which the solid waste is composted by the
use of microbes into manure which acts as a nutrient for plant growth.
·
Rhizofiltration is the uptake of metals or degradation of
organic compounds by rhizosphere microorganisms.
·
Rhizostimulation is the stimulation of plant growth by the
rhizosphere by providing better growth condition or reduction in toxic
materials.
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Only biodegradable contaminants can be transformed using
bioremediation processes.
·
Bioremediation processes must be specifically made in accordance
to the conditions at the contaminated site.
·
Small-scale tests on a pilot scale must be performed before
carrying out the procedure at the contaminated site.
·
The use of genetic engineering technology to create genetically
modified microorganism or a consortium of microbes for bioremediation process
has great potential.
Algal fuel, also known as algal biofuel, or algal oil is an
alternative to liquid fossil fuels, the petroleum products. This use algae as a
source of energy-rich oils. Also, algal fuels are an alternative to commonly
known biofuel sources obtained from corn and sugarcane. The energy crisis and
the world food crisis have initiated interest in algal culture (farming algae)
for making biodiesel and other biofuels using land unsuitable for agriculture. Botryococcus
braunii is normally used to produce algal biofuel.
Biological hydrogen production by algae
The biological hydrogen production with algae is a method of photo
biological water splitting. In normal photosynthesis the alga, Chlamydomonas
reinhardtii releases oxygen. When it is deprived of sulfur, it
switches to the production of hydrogen during photosynthesis and the electrons
are transported to ferredoxins. [Fe]-hydrogenase enzymes combine them into the
production of hydrogen gas.
Bioprospecting is the process of discovery and commercialization
of new products obtained from biological resources. Bioprospecting may involve
biopiracy, in which indigenous knowledge of nature, originating with indigenous
people, is used by others for profit, without authorization or compensation to
the indigenous people themselves.
Biopiracy can be defined as the manipulation of intellectual
property rights laws by corporations to gain exclusive control over national
genetic resources, without giving adequate recognition or remuneration to the
original possessors of those resources. Examples of biopiracy include recent
patents granted by the U.S. Patent and Trademarks Office to American companies
on turmeric, ‘neem’ and, most notably, ‘basmati’ rice. All three products are
indigenous to the Indo-Pak subcontinent.
Biopiracy of Neem
The people of India used neem and its oil in many ways to
controlling fungal and bacterial skin infections. Indian’s have shared the
knowledge of the properties of the neem with the entire world. Pirating this
knowledge, the United States Department of Agriculture (USDA) and an American
MNC (Multi Nation Corporation) W.R.Grace in the early 90’s sought a patent from
the European Patent Office (EPO) on the “method for controlling of diseases on
plants by the aid of extracted hydrophobic neem oil”. The patenting of the
fungicidal and antibacterial properties of Neem was an example of biopiracy but
the traditional knowledge of the Indians was protected in the end.
Biopiracy of Turmeric
The United States Patent and Trademark Office, in the year 1995
granted patent to the method of use of turmeric as an antiseptic agent.
Turmeric has been used by the Indians as a home remedy for the quick healing of
the wounds and also for purpose of healing rashes. The journal article
published by the Indian Medical Association, in the year 1953 wherein this
remedy was mentioned. Therefore, in this way it was proved that the use of
turmeric as an antiseptic is not new to the world and is not a new invention,
but formed a part of the traditional knowledge of the Indians. The objection in
this case US patent and trademark office was upheld and traditional knowledge
of the Indians was protected. It is another example of Biopiracy.
Biopiracy of Basmati
On September 2, 1997, the U.S. Patent and Trademarks Office
granted Patent on “basmati rice lines and grains” to the Texas-based company
RiceTec. This broad patent gives the company several rights, including
exclusive use of the term 'basmati', as well proprietary rights on the seeds
and grains from any crosses. The patent also covers the process of breeding
RiceTec’s novel rice lines and the method to determine the cooking properties
and starch content of the rice grains.
India had periled the United States to take the matter to the WTO
as an infringement of the TRIPS agreement, which could have resulted in major
embarrassment for the US. Hence voluntarily and due to few decisions take by
the US patent office, Rice Tec had no choice but to lose most of the claims and
most importantly the right to call the rice “Basmati”. In the year 2002, the
final decision was taken. Rice Tec dropped down 15 claims, resulting in
clearing the path of Indian Basmati rice exports to the foreign countries. The
Patent Office ordered the patent name to be changed to ‘Rice lines 867’.
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